Hey there Turk. You definitely didn't offend me! I've just been so busy it's crazy.

Good news on the bifrons; sounds like you ended up arranging them exactly as I have mine. In the end the only thing I really had to change about them was the hot mid-range resonances I was getting. I added a ring of putty around the whizzer cone (pressed right into the gap where the voice coil former is visible) as a terminator to damp transverse modes in the cones. This ended up having exactly the desired effect and also reduced fs a bit for better bass response. The only real drawback to this mod is a reduction in efficiency but they are still very efficient.

duo
busy is good i hope that along with the craziness there's cash!
i'm still running the original wiring scheme and drivers (other than the visaton's on the back)
and just a comparision of terms i'd be more apt to say that they have comb filtering happening in the upper mid's which colors them not resonances but i will have to try the putty thing to see.
i'll ask again what is your acoustic resistor for aperiodic tuning?
the next thing i am going to experiment with on these is to rewire them to obtain a more cohesive wave front(the original scheme places the "hot" drivers in series legs at co-incident points which doesn't help)

p.s. : i'm still trying to confirm a rumbling about a low frequency compensation circuit that was built into a companion (matching/intended) amp.

after listening to these speakers for a couple of months i still couldn't quite figure out what it was about them that made me stop and focus so intently on them.
i've now realized it's the comb filtering!

after a few quick checks with the RTA there's huge notch's in the mid range from aprox. 800 hz up to about 3khz that occur in the 17 to 48 degree region not to mention the 300 hz broad peak that i'm pretty sure is the result of too small a box ,being that it's intended as a sealed enclosure.

after some experimentation (as in running half the box and aperiodic and reflex tuning it; even trying a six inch sub driver in dipole) i'm reasonably certain that without changing the box geometry and implementing the right combination of crossover/eq they are a masterful example of how not to build a speaker!

They do have some funny frequency response effects and a nasty peak in response for sure. I improved mine dramatically by adding mass to the cones of the drivers (I may have mentioned that earlier in this thread).

After adding mass to the drivers I found an aperiodic or sealed enclosure ended up being the best thing. You still get the comb effects and the bass response lacks but regardless of empirical measurements there was a quality about the Bifrons I could never get past; most of my friends had the same impression of them.

sorry duo you can add whatever you want to the drivers or tune the box how you like; it's a bad design which would make even the best drivers you can find sound like a--!
your right i couldn't get passed the quality of comb filtering !
p.s. the drivers individually in a 1.5 liter enclosure sound awesome!

I'll agree they sucked in their stock state. And even with modifications they sound weird and can be hard to get used to. But after you get past that there's some reason I just can't stop enjoying them.